In recent years, a technique of connecting an image scanner to a computer network, scanning an original with the scanner to read the image on the original, and sending the obtained image data to the computer network as an image file has been proposed.
In transmitting image data by such an image scanner, the user selects a transmission protocol and resolution, monochrome or color mode, format, and transmission destination of the image to be transmitted from the operation section.
Examples of the transmission protocol are Simple Mail Transfer Protocol (to be referred to as SMTP hereinafter), File Transfer Protocol (to be referred to as FTP hereinafter), NetWare, and Server Message Block Protocol (to be referred to as SMB hereinafter).
The resolution of an image is defined by resolutions in the main scanning and sub-scanning directions, and for example, dot per inch (to be referred to as dpi hereinafter) is used as a unit. More specifically, when 200 dpi×100 dpi is designated, the resolution in the main scanning direction is 200 dpi, and that in the sub-scanning direction is 100 dpi.
When a monochrome image is to be acquired by scanning, for example, the single page tag image file format (to be referred to as S-TIFF hereinafter), multiple page tag image file format (to be referred to as M-TIFF hereinafter), or portable document format (to be referred to as PDF hereinafter) developed by Adobe is designated as an image format.
When a color image is to be acquired by scanning, for example, the Joint Photographic Experts Group Format (to be referred to as JPEG hereinafter) or PDF is designated. The S-TIFF and JPEG form a file from the image of one original. The M-TIFF and PDF form a file from the images of a plurality of originals.
The expression of a transmission destination changes depending on the transmission protocol. A transmission destination for SMTP means an e-mail address, and that for FTP, NetWare, or SMB means a server name and a user name, password, and directory name on the server. The name of a file to be transmitted can also be added.
In such an image scanner, when one file is to be formed from a plurality of pages, as in the M-TIFF or PDF, for example, the image memory capacity may be short. In addition, when the user inputs an interrupt instruction or the like, processing is incompletely ended for an image file which is being created for an original image read so far, so the image file cannot be used.
The reason for this is as follows. In the M-TIFF or PDF, to, e.g., designate and display an arbitrary page, an offset value is added to the end of each page, and information for determining the file is added to the end of the final page. If the processing is interrupted, such information cannot be written, and an incomplete file which cannot be processed by an application compatible to M-TIFF or PDF is formed.